Visual displays of one kind or another have been present in point of sale terminals for many years. The steadily increasing sophistication of electronics used in point of sale terminals has increased the amount of visual information which may displayed. Retailer awareness of the ability of point of sale terminals to display large amounts of information has tended to increase the amount of information which retailers desire to display.
Modern point of sale terminal hardware and software can easily generate enough visual information to be displayed on multiple displays. For example, a terminal might have two displays, one displaying the details of the transaction and another displaying promotional messages. One point of constraint which tends to inhibit the use of multiple displays is that prior art terminals typically employ one of two techniques in order to drive multiple displays. One such technique is the use of multiple video cards, one video card for each display. This approach adds expense because an additional video card is added for each added display. In addition, each video card requires an expansion slot, making the slot unavailable for other uses. Another commonly used technique is the use of special video adapter cards which are designed to drive two or more displays. These cards tend to be expensive.
Modern point of sale terminals are typically built using computers such as personal computers. Personal computers typically provide one or more data output ports that may include serial ports, wireless interfaces and ports, universal serial bus ports and the like. The data output ports allow the computers to transmit data to and receive data from other devices. For example, the universal serial bus port is widely used and allows connection to a wide variety of different devices. However, version 1.1 of the universal serial bus port in particular does not provide sufficient bandwidth for acceptable driving of a display using typical prior art video technology which is cost effective from a customer point of view.
The use of additional hardware, or specialized, expensive hardware to enable a terminal to drive two or more displays limits the appeal of the terminal because retailers who need only a single display will not wish to pay for the added capability provided by a terminal that can drive two or more displays. However, it will be recognized that even retailers presently needing only one display may greatly desire the flexibility of adding one or more additional displays in the future if that flexibility is achieved at little or no additional cost for the initial purchase of the terminal. Furthermore, the retail business is a highly competitive and cost conscious so that even retailers wanting two or more displays will want them at the lowest possible cost. There exists, therefore, a need for techniques which allow a terminal to be optionally configured to drive two or more displays without a need to build additional hardware into the terminal, and which allow the terminal to transmit video data to two or more displays using standard output ports commonly included in computers used in point of sale terminals.